Susanna McLeod
Special to Canadian Design and Construction Report
The researchers and construction company staff must have been euphoric. At last, years of scientific chiselling, detection, and recording at the Tomlinson Group quarry were worthwhile. The complete body and legs of a small fossilized animal emerged, an animal that lived in the Ordovician Period 450 million years ago. It has never been found before in Ontario.
It’s not every day that a prehistorical find is made at a worksite, and even less often that the firm’s name is added to the fossil record. Announced four years ago, scientists working at the southern Ontario quarry discovered the fossil of a new species of marrellomorph arthropod. It was named Tomlinsonus dimitrii in honour of the location The extinct small soft-bodied creature existed millions of years before dinosaurs thrived throughout North America, plodding in herds or walking side by side (The earliest North American dinosaurs appeared in the Triassic Period, from 230 to 210 million years ago.)
The region near Brechin, Ontario was known for being rich with fossils for over a century. The quarry in the Lake Simcoe area is among Tomlinson’s 25 licenced quarries and pits to excavate aggregates for roadways and other projects. Independent paleontologist technician George Kampouris has painstakingly examined the Brechin stone quarry site for fossils since 2014.
Limestone, sandstone, shale, and other sedimentary rocks lie under a thick deposit of gravel and sand. Southern Ontario’s bedrock “began as mud and limy oozes at the bottom of a shallow, tropical sea between 360 and 500 million years ago,” according to University of Waterloo’s “Paleozoic fossils in Ontario.” Eons passed. Sediment particles hardened together, turning the shallow burial grounds of marine creatures into lithified fields of fossils.
Brechin Quarry is part of the Kirkfield Formation, making up “the middle portion of the Simcoe Group,” and “dominated by carbonate facies, representing offshore shoal to shallow marine environments (around the tens of meters of water),” wrote researcher Joseph Moysiuk et al in “A new marrellomorph arthropod from southern Ontario” in Journal of Paleontology, March 24, 2022.
Technician Kampouris was searching for shelled creatures such as trilobites and sea lilies. (A sea lily is not a plant, but a marine animal related to starfish in the class Crinoidea.) “Our work here has revealed the role of catastrophic storm events in the burial and preservation of entire animal communities in their final moments,” Kampouris mentioned to Ashima Agnihotri in Windsor Today, April 18, 2022. Time-consuming and arduous, the palaeontologist technician “worked with chisels and hammers, and systematically excavated different layers of shale and limestone.”
Kampouris observed a well-preserved fossil of an unfamiliar creature. It was “no longer than an index finger,” according to Royal Ontario Museum. (ROM) “This new species belongs to an extinct group of soft-bodied arthropods called marrellomorphs.” Astonishing in Ontario, marrellomorphs are “better known from older fossil sites like the famous Cambrian Burgess Shale in British Columbia.” The discovery delighted palaeontologists across the country.
A slow-moving creature, Tomlinsonus dimitrii is thought to be benthic, meaning bottom-dwelling, scavenging its morsels of dinner from detritus on the sea floor. Moysiuk told Live Science that the fossil has no eyes and “appears to be blind.” He also mentioned that “underneath the head, there is an amazing pair of limbs that are extremely long and have foot-like projection at the terminal ends, which we think it most likely used to stilt its way across the seafloor,” reported BBC News, April 26, 2022.
The extinct invertebrate “has an ornate head shield adorned with remarkable feather-like spines,” ROM described. ‘“This strange-looking animal probably negotiated the muddy seafloor using a pair of exceptionally long, stilt-like limbs,’” noted Moysiuk, based at the ROM.
Adding to the excitement of a new species, fossils of soft-bodied animals are an extraordinary find. The hard parts of creatures become fossilized such as the mineralized bones and shells. The soft parts, such as internal structures and gills, normally break down in decay by scavengers and bacteria. “The soft-bodied fossils of the Brechin area represent a rare window into Ordovician open ocean shelf environments in North America,” stated the ROM. “The researchers believe Brechin offers great potential for further similar discoveries.”
Sharing news of the exciting earth science development, Tomlinson Group’s Instagram post in 2022 announced, “Meet the oldest species of the Tomlinson team.” The construction firm has been exceptionally helpful with the science community, permitting comprehensive excavation of large areas. Examining quarry areas layer by rocky layer, the scientists have endeavoured to reconstruct the prehistoric seafloor. Every fossil discovery adds information to the expanding geological records of southern Ontario to better understand our world.
The Royal Ontario Museum at 100 Queen’s Park in Toronto has added Tomlinsonus dimitrii to their illuminating collections. On display in the Willner Madge Gallery: Dawn of Life, the remarkable fossil is adding another chapter in evolutionary history.
© Susanna McLeod 2026 is a Kingston-based writer specializing in Canadian history.
Sources:
Agnihotri, Ashima, “New fossil on display at ROM predates dinosaurs and was discovered near Orillia,” Orillia Today/Toronto Star, April 18, 2022. https://www.ourwindsor.ca/news/new-fossil-on-display-at-rom-predates-dinosaurs-and-was-discovered-near-orillia/article_a28687e6-6235-50a1-917e-517669e4ec41.html?
Moysiuk, Joseph; Izquierdo-Lopez, Alejandro; Kampouris, George E.; Caron, Jean-Bernard.
“A new marrellomorphs arthropod in southern Ontario: a rare case of soft-tissue preservation on a Late Ordovician open marine shelf,” Journal of Palaeontology, March 24, 2022.
“Newsround: Check out the ancient sea creature which walked on stilts!” BBC, April 26, 2022. https://www.bbc.co.uk/newsround/61207417
“Palaeozoic fossils in Ontario,” University of Waterloo. https://uwaterloo.ca/earth-sciences-museum/educational-resources/fossils/paleozoic-fossils-ontario
“Remarkably preserved 450-million-year-old marine animal discovered in Ontario,” Royal Ontario Museum (ROM), April 19, 2022. https://www.rom.on.ca/news-releases/remarkably-preserved-450-million-year-old-marine-animal-discovered-ontario
